Rf crossover apparatus for microwave systems

ABSTRACT

An RF crossover apparatus provides low transmission and return losses for microwave systems and meets the requirement for the RF signals to leap over each other as in an insulated state. The RF crossover apparatus contains a body produced from ceramic material, at least two RF strips placed inside the body in a way to intersect each other and at least one insulation layer insulating the RF strips placed on the body at least from the external environment. The body produced from ceramic material enables operation on high frequencies and this provides low transmission and return losses. The RF crossover apparatus also contains matching circuits on the tips of the RF strips for the RF strips to be passed to chip devices during use.

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is the national phase entry of International Application No. PCT/TR2018/050292, filed on Jun. 7, 2018, which is based upon and claims priority to Turkish Patent Application No. 2017/08558, filed on Jun. 9, 2017, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention is related to an RF (radio frequency) crossover apparatus used for low transmission and return losses in microwave systems.

BACKGROUND

Microwaves are waves having a wavelength between 1 mm and 1 m, in other words, having frequency between 300 GHz and 300 MHz. These waves are used especially in telecommunication systems, navigation systems, radars and astronomy.

Since the wavelengths of microwaves are nearly the same with the dimensions of the devices carrying the microwaves, the classical circuit theory loses validity in microwave electronics. When they come across with an obstacle at the level of their wavelengths, microwaves can overcome this obstacle and this results in serious problems with the insulation. Particularly, the insulations of the parts which are supposed to cross each other in the circuit paths where the microwave signals are transmitted remain weak and this weakness causes noise in the transmitted signal.

In the state of art, some methods have been developed in order to overcome this problem. For instance, paths which are supposed to leap over each other are transferred to a coaxial cable of microstrip and the crossover is provided as such. The crossover structure is large in this method and in addition, the transmission and return losses are excessive.

Another method in the state of art is enabled by ensuring that a line is crossed over another line by the use of gold strip. With this method, crossover band width is narrow and the insulation is poor.

In the RF (radio frequency) crossovers used for providing low transmission and return losses in microwave systems, the insulation between the channels need to be as high as possible. In addition, interference which could be originating externally also causes noise in RF signals. For this reason, RF crossovers need to be also isolated from the external environment. In addition to that, the RF crossover needs to have high electrical performance. Aside from all these, high frequency microwave systems require dimensionally small crossover structures and the RF crossover structures used for mass production microwave systems should be cost-efficient.

A ceramic based RF structure is mentioned in the United States patent document numbered US2014159836 in the state of art. In this structure, there is a ceramic based body and a strip line structure inside the body. However, RF strips crossing over each other do not take place in the embodiment.

SUMMARY

An RF crossover apparatus meets the requirement for the RF signals to leap over each other as in an insulated state and provides low transmission and return losses for microwave systems is developed with the present invention. The RF crossover apparatus contains a body produced from ceramic material, at least two RF strips placed inside the body in a way to intersect each other and at least one insulation layer which provides for the RF strips placed on the body to be insulated at least from the external environment. The body produced from ceramic material enables operation on high RF and this provides for obtaining the low transmission and return losses. The RF crossover apparatus also contains matching circuits on the tips of the RF strips which provide for the RF strips to be passed on to chip devices during use.

In an embodiment of the invention, the RF crossover apparatus contains more than one bodies assembled together by being placed on each other. In this embodiment of the invention, the subject RF crossover apparatus is produced by baking the bodies at high temperatures and piecing them together. With the purpose of providing the bodies with equipotential earthing, earthing layer is applied on the outside facing surfaces of the bodies.

The purpose of the present invention is to provide an RF crossover apparatus for low transmission and return losses in microwave systems.

Another aim of the invention is to provide an RF crossover apparatus which eliminates the requirement of an additional matching circuit for chip devices in microwave systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The application of the RF crossover apparatus for a microwave system developed with the present invention is shown in the attached figures for illustration purposes.

FIG. 1 is the perspective view of the RF crossover apparatus.

FIG. 2 is the top schematic view of the RF crossover apparatus.

FIG. 3 is the cross-sectional view of a multilayer structure obtained by using RF crossover apparatuses.

The parts in the figures are numbered and their references are given below:

RF crossover apparatus (A) Body (1) RF strip (2) Insulation layer (3) Base part (4) Protective part (5) Matching circuit (6) Earthing layer (7)

DETAILED DESCRIPTION OF THE EMBODIMENTS

The illustrative embodiments of the RF crossover apparatus (A) are presented in FIGS. 1-3 and is suitable for use in microwave systems and it comprises; at least one body (1), at least two RF strips (2) transmitting RF signals and placed on the body (1) so as to intersect each other and an insulation layer (3) takes place on at least one surface of the body (1) facing the external environment and insulating the RF stripes (2) from the external environment. The body (1) of the RF crossover apparatus contains a base part (4) on which RF stripes (2) are placed and at least one protective part (5) integrated with the base part (4) and extending outwards from the base part (4) in a way to at least partially cover the RF stripes (2) placed on the base part (4). In the preferred embodiment of the invention, at least one of the RF stripes (2) does not have contact with the protective part (5). In a derivative of the preferred embodiment of the invention, the RF stripe (2) intersecting with the RF stripe (2) which does not contact the protective part (5) extends towards the protective part (5) at the intersection point of the RF stripes (2) and in this state, the two RF stripes (2) intersect with an approximately 90 degrees angle. The body (1) containing the base part (4) and protective part (5) in the RF crossover apparatus (A) is produced from ceramic material which enables the RF stripes (2) to operate on high frequencies (i.e. over 30 GHz). In a preferred specific embodiment of the invention, the body (1) is produced from a ceramic material which is low temperature sintered ceramic based (LTCC_Low Temperature Cofired Ceramic). In the preferred embodiment of the invention, the insulation layer (3) takes place on the surface of the protective part (5) which does not face RF stripes (2). The insulation layer (3) contains at least one perforated transition decreasing the transmission losses and increasing the spectral band by increasing insulation between the RF earthing material and RF stripes (2).

In the preferred embodiment of the invention, RF crossover apparatus (A) also contains matching circuits (6) that provide transmission to chip devices used in microwave systems on the tips of the RF strips (2) on the body (1) base part (4). In the preferred embodiment of the invention, the matching circuits (6) are configured in a way to provide impedance matching with the chip devices.

Thanks to the subject matching networks (6), operation of the crossover between the RF strips (2) on wide frequency band and low transmission and return losses are obtained in the RF crossover apparatus (A). In addition to all of these, the necessity for an additional matching circuit for the chip devices during applications is eliminated and applications become easier.

In an embodiment of the invention the RF crossover apparatus (A) contains more than one bodies (1) placed on each other (FIG. 3). In this embodiment of the invention, the bodies (1) are connected together by baking at high temperatures (i.e. over 800° C.) and by this means, a durable and hermetic structure is obtained. In the subject embodiment, there is at least one earthing layer (7) on the outside facing surfaces of the bodies (1) to provide equipotential earthing between the bodies (1). The earthing layer (7) is applied to the external surfaces of the bodies (1) after the bodies (1) are assembled together. In this embodiment of the invention, the insulation layer (3) preferably taking place on the protective layer (5) also provides the insulation between the RF strips in the bodies (1).

The RF crossover apparatus (A) enables to operate in high frequency thanks to the body (1) produced from ceramic material. In this way, low transmission and return losses are provided. The subject RF crossover apparatus (A) also protects the RF strips (2) against the noise that could be originating from the exter 

What is claimed is:
 1. A radio frequency (RF) crossover apparatus suitable for a use with microwave systems, comprising at least one body, at least two RF strips transmitting RF signals and placed to intersect each other on the body, and at least one insulation layer, wherein the at least one insulation layer is placed on at least one surface of the body and insulates the RF strips at least from an external environment, and the body is formed of a ceramic material and is configured for an operation in high frequencies.
 2. The RF crossover apparatus according to claim 1, wherein the ceramic material is a ceramic based material sintered at low temperatures.
 3. The RF crossover apparatus according to claim 1, wherein the body comprises a base part, wherein the at least two RF strips are placed on the base part; and at least one protective part, wherein the at least one protective part is integrated with the base part and extends outwards from the base part, and at least partially covers the at least two RF strips placed on the base part.
 4. The RF crossover apparatus according to claim 3, wherein at least one RF strip inside the body does not come in contact with the at least one protective part.
 5. The RF crossover apparatus according to claim 4, the at least one RF strip extends towards the at least one protective part at an intersection point of the at least two RF strips.
 6. The RF crossover apparatus according to claim 3, wherein the at least one insulation layer is located on a surface of the at least one protective part, wherein surface of the at least one protective part does not face the at least two RF strips.
 7. The RF crossover apparatus according to claim 1, wherein the at least one insulation layer comprises at least one perforated transition configured to increase a spectral band and decreasing transmission losses by increasing an insulation between a RF earthing material and the at least two RF strips.
 8. The RF crossover apparatus according to claim 1, further comprising a matching circuit, wherein the matching circuit provides transmission to chip devices provided in the microwave systems on tips of the at least two RF strips on the body.
 9. The RF crossover apparatus according to claim 8, wherein the matching circuits is configured in a way to provide impedance matching with the chip devices.
 10. The RF crossover apparatus according to claim 1, wherein the at least one body includes a plurality of bodies placed on each other.
 11. The RF crossover apparatus according to claim 10, further comprising at least one earthing layer on outside facing surfaces of the plurality of bodies for providing equipotential earthing between the plurality of bodies.
 12. A method of obtaining an RF crossover apparatus suitable for use in microwave systems according to claim 10, comprising the steps of assembling the plurality of bodies by baking on high temperatures and applying an earthing layer on outer surfaces of the plurality of bodies after the plurality of bodies are assembled.
 13. The RF crossover apparatus according to claim 2, wherein the body comprises a base part, wherein the at least two RF strips are placed on the base part; and at least one protective part, wherein the at least one protective part is integrated with the base part and extends outwards from the base part, and at least partially covers the at least two RF strips placed on the base part.
 14. The RF crossover apparatus according to claim 5, wherein the at least one insulation layer is located on a surface of the at least one protective part, wherein surface of the at least one protective part does not face the at least two RF strips. 